A power semiconductor module of ultrasonic welded copper ribbons

Abstract

The utility model provides a kind of power semiconductor module of ultrasonic welding copper band, it is related to power semiconductor module packaging technical field, including heat dissipation substrate, at least one metallized ceramic substrate is equipped on the heat dissipation substrate;At least one copper band, the welding end of the copper band is welded on the upper surface of the metallized ceramic substrate by ultrasonic, and the connecting end of the copper band is connected with the end of the heat dissipation substrate.Beneficial effect is that copper band is connected with metallized ceramic substrate by ultrasonic welding mode, effectively avoid the residue pollution caused by traditional solder connection, unstable welding quality, welding defects (virtual welding, cold welding, bridging, etc.) and product oxidation and other problems, and ultrasonic welding can realize the close combination of intermetallic covalent bond through tiny friction in a short time, which can effectively reduce the deformation and stress concentration of materials, improve the welding strength and reliability.

Description

Technical Field

[0001] This utility model relates to the field of power semiconductor module packaging technology, and in particular to a power semiconductor module with ultrasonically welded copper strip. Background Technology

[0002] In traditional power device packaging processes, solder paste is typically used to connect copper strips to metallized ceramic substrates. However, this technology has several technical shortcomings that urgently need to be addressed in practical applications, specifically in the following aspects:

[0003] 1) Solder residue exists. After the reflow soldering process, solder paste material leaves residues that are difficult to remove at the solder interface and surrounding areas. These residues not only contaminate the product surface but may also substantially interfere with subsequent precision processes such as chip mounting and wire bonding, significantly reducing production yield.

[0004] 2) Unstable soldering quality. The volatility in soldering quality stems primarily from two dimensions: Firstly, the selection of solder paste materials lacks scientific standards, with solder pastes of different component ratios exhibiting significant differences in flowability and wettability. Secondly, the process parameter control system has deficiencies, including a lack of precise control mechanisms for key parameters such as temperature profile settings, pressurization timing, and duration. This dual uncertainty easily leads to premature drying or insufficient wetting of the solder paste, directly causing a decrease in the reliability of the solder interface.

[0005] 3) Products after reflow soldering exhibit welding defects such as incomplete soldering, cold soldering, and bridging. Incomplete soldering, a common problem after reflow soldering, is often related to insufficient uniformity control of the solder paste application. When the amount of solder paste falls below a critical value, a joint with insufficient mechanical strength will form. Cold soldering defects mainly stem from temperature parameter imbalances. Whether it's excessively high temperatures leading to alloy coarsening or excessively low temperatures causing insufficient diffusion, both significantly weaken the mechanical properties of the solder joint. Furthermore, bridging defects expose technical bottlenecks in solder paste printing accuracy and position control.

[0006] 4) Oxidation problem. In high-temperature process environments, the active metal components (especially tin) in solder paste undergo irreversible chemical reactions with oxygen, forming a micro-oxide layer at the soldering interface. This oxide layer not only increases contact resistance and affects the conductivity of the device, but also damages the metallurgical bond between metals, resulting in a significant reduction in solder strength of approximately 30%-40%.

[0007] In addition to the above problems, other defects such as solder balls, short circuits, misalignment, and empty solder joints may occur. For example, if the reflow soldering temperature rises too quickly, solder balls may be generated.

[0008] Therefore, a new type of connection method is needed to effectively avoid the above situation. Utility Model Content

[0009] To address the problems existing in the prior art, this utility model provides a power semiconductor module for ultrasonic welding of copper strips, comprising:

[0010] A heat dissipation substrate, wherein at least one metallized ceramic substrate is disposed on the heat dissipation substrate;

[0011] At least one copper strip, the welding end of which is ultrasonically welded to the upper surface of the metallized ceramic substrate, and the connecting end of which is connected to the end of the heat dissipation substrate.

[0012] Preferably, the metallized ceramic substrate comprises:

[0013] A first copper layer is disposed on the upper surface of the heat dissipation substrate;

[0014] A ceramic layer is disposed on the upper surface of the first copper layer;

[0015] A second copper layer is disposed on the upper surface of the ceramic layer, and the welding end of the copper strip is ultrasonically welded to the upper surface of the second copper layer.

[0016] Preferably, the welding area at the welding end of the copper strip and the welding area on the second copper layer corresponding to the welding end are both made of copper material.

[0017] Preferably, the upper surface of the second copper layer is further provided with a plurality of semiconductor chips and a plurality of thermistors.

[0018] Preferably, each of the semiconductor chips and each of the thermistors are soldered to the upper surface of the second copper layer using solder.

[0019] Preferably, there are multiple copper strips, and the connecting ends of each copper strip are located at the same end of the heat dissipation substrate or at both ends of the heat dissipation substrate.

[0020] Preferably, there are seven copper strips, and the connecting ends of each copper strip are located at both ends of the heat dissipation substrate.

[0021] Preferably, the metallized ceramic substrate is soldered to the upper surface of the heat dissipation substrate using solder.

[0022] Preferably, the area of ​​the metallized ceramic substrate is smaller than the area of ​​the heat dissipation substrate.

[0023] The above technical solution has the following advantages or beneficial effects: the copper strip is connected to the metallized ceramic substrate by ultrasonic welding, which effectively avoids the problems of residual contamination, unstable welding quality, welding defects (cold welding, bridging, etc.) and product oxidation caused by traditional solder connection. In addition, ultrasonic welding can achieve tight bonding of covalent bonds between metals through micro-friction in a short time, which can effectively reduce material deformation and stress concentration, and improve welding strength and reliability. Attached Figure Description

[0024] Figure 1 A top view of a power semiconductor module for ultrasonic welding of copper strips is provided in a preferred embodiment of this utility model.

[0025] Figure 2 A cross-sectional view of a power semiconductor module for ultrasonic welding of copper strips is shown in a preferred embodiment of this utility model.

[0026] In the attached figure, 1 is a heat dissipation substrate; 2 is a metallized ceramic substrate; 21 is a first copper layer; 22 is a ceramic layer; 23 is a second copper layer; 3 is a copper strip; 31 is a welding end; 32 is a connection end; 4 is a semiconductor chip; 5 is a thermistor; and 6 is solder. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within its scope.

[0028] In a preferred embodiment of this utility model, based on the above-mentioned problems existing in the prior art, a power semiconductor module for ultrasonic welding of copper strips is provided, such as... Figure 1 and Figure 2 As shown, it includes:

[0029] A heat dissipation substrate 1, on which at least one metallized ceramic substrate 2 is disposed;

[0030] At least one copper strip 3, the welding end 31 of the copper strip 3 is ultrasonically welded to the upper surface of the metallized ceramic substrate 2, and the connecting end 32 of the copper strip 3 is connected to the end of the heat dissipation substrate 1.

[0031] Specifically, in this embodiment, the copper strip 3 is connected to the metallized ceramic substrate 2 by ultrasonic welding, which has the following significant advantages compared with traditional solder paste welding:

[0032] 1) No solder residue: Ultrasonic welding is a solid bonding technology that does not require solder paste or flux, completely avoiding the problem of residue contamination in traditional welding processes and ensuring the cleanliness of subsequent processes (such as chip mounting, bonding, etc.).

[0033] 2) Stable welding quality: Ultrasonic welding uses high-frequency vibration friction to form metallic covalent bonds at the interface of copper materials, which is not affected by fluctuations in solder paste composition, temperature profile or reflow process, and greatly reduces defects such as cold solder joints, cold solder joints and bridging.

[0034] 3) Strong oxidation resistance: Since the soldering process is completed at a low temperature (far below the melting point of solder paste) and does not need to be exposed to a high-temperature oxidation environment, the interface between the copper layer and the copper strip 3 is not prone to forming an oxide film, ensuring long-term conductivity and mechanical strength.

[0035] 4) Low-stress connection: The local micro-friction of ultrasonic welding only occurs in the welding area and will not cause overall thermal deformation of the substrate or copper strip, effectively reducing thermal stress concentration and improving the long-term reliability of the packaging structure.

[0036] In summary, the copper strip 3 is connected to the metallized ceramic substrate 2 by ultrasonic welding, which effectively avoids problems such as residual contamination, unstable welding quality, welding defects (cold welding, bridging, etc.) and product oxidation caused by traditional soldering. Furthermore, ultrasonic welding can achieve tight bonding of covalent bonds between metals through micro-friction in a short time, which can effectively reduce material deformation and stress concentration, and improve welding strength and reliability.

[0037] In a preferred embodiment of this invention, the metallized ceramic substrate 2 comprises:

[0038] The first copper layer 21 is disposed on the upper surface of the heat dissipation substrate 1;

[0039] A ceramic layer 22 is disposed on the upper surface of the first copper layer 21;

[0040] The second copper layer 23 is disposed on the upper surface of the ceramic layer 22, and the welding end 31 of the copper strip 3 is ultrasonically welded to the upper surface of the second copper layer 23.

[0041] Specifically, in this embodiment, the metallized ceramic substrate 2 is fabricated using a metallized ceramic process, consisting of a first copper layer 21, a ceramic layer 22, and a second copper layer 23 arranged sequentially from bottom to top. By directly soldering the first copper layer 21 to the heat dissipation substrate 1, a low thermal resistance path is formed, allowing heat to be quickly conducted to the bottom heat dissipation system via the ceramic layer 22, making it suitable for high-power devices. The ceramic layer 22 provides excellent electrical isolation performance while also possessing high mechanical strength, ensuring the stable operation of the chip 4 and circuits on the second copper layer 23.

[0042] In a preferred embodiment of this invention, both the welding area of ​​the welding end 31 of the copper strip 3 and the welding area on the second copper layer 23 corresponding to the welding end 31 are made of copper material, enabling atomic-level metallurgical bonding during ultrasonic welding, resulting in extremely low interface resistance and superior fatigue resistance compared to solder joints. In another preferred embodiment of this invention, the upper surface of the second copper layer 23 is further provided with multiple semiconductor chips 4 and multiple thermistors 5.

[0043] Specifically, in this embodiment, the number of semiconductor chips 4 and thermistors 5 is not limited, and the number can be customized according to requirements.

[0044] In a preferred embodiment of the present invention, each semiconductor chip 4 and each thermistor 5 are soldered to the upper surface of the second copper layer 23 using solder.

[0045] In a preferred embodiment of the present invention, there are multiple copper strips 3, and the connecting ends 32 of each copper strip 3 are located at the same end of the heat dissipation substrate 1 or at both ends of the heat dissipation substrate 1 respectively.

[0046] Specifically, in this embodiment, by configuring multiple copper strips 3, the copper strips 3 can be distributed on one or both ends of the heat dissipation substrate 1, flexibly adapting to the current distribution requirements of different power circuits and reducing the risk of local overheating.

[0047] In a preferred embodiment of this utility model, there are seven copper strips 3, and the connecting ends 32 of each copper strip 3 are located at both ends of the heat dissipation substrate 1.

[0048] In a preferred embodiment of this invention, the metallized ceramic substrate 2 is soldered to the upper surface of the heat dissipation substrate 1 by solder 6, which takes into account both high thermal conductivity and structural strength, while the copper strip 3 is ultrasonically welded to form a hybrid connection system that combines the advantages of the two technologies.

[0049] In a preferred embodiment of the present invention, the area of ​​the metallized ceramic substrate 2 is smaller than the area of ​​the heat dissipation substrate 1, ensuring that the edge of the heat dissipation substrate 1 can serve as a mechanical fixing or auxiliary heat dissipation area, while avoiding stress cracking caused by thermal expansion mismatch.

[0050] The above description is only a preferred embodiment of the present utility model and does not limit the implementation method and protection scope of the present utility model. Those skilled in the art should realize that all solutions obtained by equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present utility model.

Claims

1. A power semiconductor module for ultrasonic welding of copper strips, characterized in that, include: A heat dissipation substrate, wherein at least one metallized ceramic substrate is disposed on the heat dissipation substrate; At least one copper strip, the welding end of which is ultrasonically welded to the upper surface of the metallized ceramic substrate, and the connecting end of which is connected to the end of the heat dissipation substrate; The metallized ceramic substrate includes: A first copper layer is disposed on the upper surface of the heat dissipation substrate; A ceramic layer is disposed on the upper surface of the first copper layer; A second copper layer is disposed on the upper surface of the ceramic layer, and the welding end of the copper strip is ultrasonically welded to the upper surface of the second copper layer.

2. The power semiconductor module according to claim 1, characterized in that, The welding area at the welding end of the copper strip and the welding area on the second copper layer corresponding to the welding end are both made of copper.

3. The power semiconductor module according to claim 1, characterized in that, The upper surface of the second copper layer is also provided with multiple semiconductor chips and multiple thermistors.

4. The power semiconductor module according to claim 3, characterized in that, Each of the semiconductor chips and each of the thermistors are soldered to the upper surface of the second copper layer using solder.

5. The power semiconductor module according to claim 1, characterized in that, There are multiple copper strips, and the connecting ends of each copper strip are located at the same end of the heat dissipation substrate or at both ends of the heat dissipation substrate.

6. The power semiconductor module according to claim 5, characterized in that, There are seven copper strips, and the connecting ends of each copper strip are located at both ends of the heat dissipation substrate.

7. The power semiconductor module according to claim 1, characterized in that, The metallized ceramic substrate is soldered to the upper surface of the heat dissipation substrate.

8. The power semiconductor module according to claim 1, characterized in that, The area of ​​the metallized ceramic substrate is smaller than the area of ​​the heat dissipation substrate.

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